The present invention disclosed herein relates to an apparatus and method for treating a substrate, and more particularly, to a rotatable spin head configured to support a substrate, for example, in a semiconductor process, and an apparatus for treating a substrate using the spin head.
Semiconductor processes include a process of etching or cleaning thin layers, foreign substances, and particles. Such an etching or cleaning process may be performed by placing a substrate such as a wafer on a spin head with a patterned side of the wafer facing upward or downward and supplying a treating liquid to the wafer while rotating the spin head at high speed. The spin head includes chuck pins to support the edge of the wafer for preventing the wafer from being detached from the spin head in a radial direction. The chuck pins can be moved between rest positions and supporting positions. When the chuck pins are in the rest positions, a space for loading and unloading a substrate on the spin head is formed. When a substrate loaded on the spin head is treated while rotating the spin head, the chuck pins are in supporting positions where the chuck pins make contact with the edge of the substrate and support the substrate. A space defined among the chuck pins in the rest positions is larger than a space defined among the chuck pins in the supporting positions.
In general, the chuck pins are moved together from the rest positions to the supporting positions by a single driving mechanism. However, the chuck pins may be non-uniform in size since machining tolerances are allowed in a manufacturing process. In this case, although all the chuck pins are moved together to the supporting positions, some of the chuck pins may not make contact with the edge of a substrate placed on the spin head. Thus, the substrate can be unstably supported, and the other chuck pins making contact with the edge of the substrate can be easily damaged due to concentration of stress.
In addition, if the spin head is rotated at high speed, since a strong centrifugal force is applied to the chuck pins in a direction from the supporting positions to the rest positions, a substrate loaded on the spin head may be unstably supported by the chuck pins.
Generally, the spin head includes an upper plate and a lower plate that are joint together using screws, and the chuck pins are installed on the lower plate with upper portions of the chuck pins being protruded upward through the upper plate. Since chemicals are used as treating liquids in a substrate treating process, the upper plate is generally formed of a corrosion resistant material such as polyvinylchloride. However, if chemicals are used at high temperatures, the upper plate formed of polyvinylchloride may be readily deformed by heat. When the upper plate expands due to thermal deformation, the lower plate coupled to the upper plate using screws may also expand. This alters positions of the chuck pins installed on the lower plate.